Chimeric virus-like particle or chimeric capsomers from BPV

ABSTRACT

The present invention relates to chimeric virus-like particles (cVLPs) or chimeric capsomers (cCs) from BPV, fusion proteins and DNAs coding for said proteins and to the use of cVLPs or cCs for the immunization of ungulates, especially horses.

This application is a National Stage of International Application PCT/DE00/00426, filed Feb. 10, 2000; which claims the priority of DE 199 05 88.30, filed Feb. 11, 1999.

The present invention relates to chimeric virus-like particles (cVLPs) or chimeric capsomers (cCs) from BPV, fusion proteins and DNAs coding for said proteins as well as the use of the cVLPs or the cCs for the immunization of ungulates, especially horses.

Sarcoids frequenztly occur in ungulates, in particular horses. They are exophytically growing skin tumors which may be localized on various parts of the body. Sarcoids often have sequences of bovine papilloma viruses (BPVs). Sarcoids are usually removed by means of an operation, which due to their localization, e.g. at the eye or ear, is often difficult. Sarcoids also have a high recurrence rate, thus representing a considerable problem for veterinary surgeons, breeders and owners.

It is thus the object of the present invention to provide a product serving for taking steps against sarcoids, the above drawbacks being avoided.

According to the invention this is achieved by the subject matters defined in the claims.

The present invention is based on Applicant's insights that cVLPs or cCs from BPV, the latter being incomplete cVLPs, are suitable for taking prophylactic and therapeutic steps against sarcoids of ungulates, in particular horses. Such cVLPs or cCs contain fusion proteins which comprise fragments of L1 or L2 proteins from BPV and early proteins from BPV, e.g. E6 or E7 proteins, or fragments thereof. He realized that antibodies can be induced by the cVLPs or cCs or cytotoxic T cells can be stimulated which are directed against BPV. He also realized that an infection caused by BPV can be prevented by the antibodies and a rejection of the sarcoids and the BPV-infected cells can be achieved by the cytotoxic T cells.

According to the invention Applicant's insights are utilized to use cVLPs or cCs from BPV for immunizing undulates against sarcoids, the cVLPs or cCs containing fusion proteins comprising fragments of L1 or L2 proteins from BPV and early proteins from BPV, e.g. E6 or E7 proteins, or fragments thereof.

The term “BPV” comprises any types of BPV, in particular the types BPV1 and BPV2.

The term “fragments of L1 or L2 proteins from BPV” comprises any fragments of these proteins which may fold or collect to form cVLPs or cCs. It may be favorable for the fragments to also be able to induce the formation of antibodies directed against BPV. Preferred fragments are those comprising amino acid sequences 1-469 or 1-472 of the L1 protein. The fragments may also differ from the corresponding wild-type fragments by one or more amino acids. This may show in terms of additions, deletions, substitutions and/or inversions of individual amino acids. In particular, the fragments may include amino acids which support the formation of cVLPs or cCs or the induction of antibodies directed against BFV.

The expression “fragments of E6 or E7 proteins from BPV” comprises any fragments of these proteins which contain epitopes for cytotoxic T cells and can be folded or collected by fusion with the above fragments of the L1 or L2 proteins to form cVLPs or cCs. Preferably the fragments do not have more than 55 amino acids. It is especially preferred for the fragments of E6 proteins from BPV1 or BPV2 to include amino acid sequences 1-55, 47-101 or 83-137. Fragments of E7 proteins from BPV1 or BPV2 preferably include the amino acid sequences 1-54, 46-100 or 72-127. The fragments may also differ from the corresponding wild-type fragments by one or more amino acids. This may show in terms of additions, deletions, substitutions and/or inversions of individual amino acids. In particular, the fragments may include amino acids which support the formation of cVLPs or cCs or the stimulation of cytotoxic T cells directed against. BPV.

The term “cVLPs or cCs from BPV” comprises any cVLPs or cCs containing fusion proteins which comprise the above fragments of L1 or L2 proteins from BPV and early proteins from BPV, e.g. E6 or E7 proteins, or the above fragments thereof. cVLPs or cCs may be provided by common methods. For example, the DNAs coding for the individual fragments or proteins may be linked to one another in a ligase reaction. The resulting DNA molecules can be expressed in cells, e.g. E. coli, yeast, mammalian or insect cells so as to obtain fusion proteins which can fold or collect to form cVLPs or cCs. It may be favorable to express the DNA molecules coding for the fusion proteins in the presence of virus DNA, e.g. vacciniavirus or baculovirus DNA, the expression with the baculovirus DNA being preferred. Reference is made to the below examples. Resulting cVLPs or cCs may contain one or more types of fusion proteins, wherein the fusion proteins of several types can differ as regards the fragments of the L1 or L2 proteins and the early proteins or the fragments thereof. The cVLPs or cCs may be isolated by common methods, e.g. density gradient centrifugation.

The expression “ungulates” comprises any kind of hoofed animals, in particular horses, cattle and game.

The term “immunization of ungulates against sarcoids” comprises any methods by means of which it is possible to induce antibodies in ungulates by the above cVLPs or cCs or stimulate cytotoxic T cells directed against BPV. It may be favorable to inject about 100 μg-1 mg of the cVLPs or cCs per animal. It may also be favorable to carry out a booster injection with about the same amount after about 14 days. In this case, it may be particularly favorable to use L1 or L2 fragments of different BPV types for the individual injections. Antibodies directed against BPV or cytotoxic T cells can be detected by common methods. For example, reference is made to Roden et al., Journal of Virology, (November 1994), 7570-7574, or Brostrom et al., Am. J. Vet. Res. 7, (July 1996), 992-999.

Another subject matter of the present invention is a cVLP or cC from BPV, which contains a fusion protein comprising the amino acid sequence of FIG. 1 or FIG. 2 or an amino acid sequence differing therefrom by one or more amino acids.

The expression “an amino acid sequence differing by one or more amino acids” indicates that the partial sequences of its individual fragments differ from the corresponding partial sequences of the fusion protein of FIG. 1 or FIG. 2. The differences may show in terms of additions, deletions, substitutions and/or inversions of individual amino acids. Reference is also made to the above statements on the individual fragments.

Another subject matter of the present invention is a fusion protein contained in the above cVLP or cC. The above explanations apply correspondingly to this fusion protein.

Another subject matter of the present invention is a nucleic acid coding for an above fusion protein. The nucleic acid may be an RNA or a DNA. A DNA is preferred which comprises the following:

-   -   (a) the DNA of FIG. 1 or FIG. 2 or a DNA differing therefrom by         one or more base pairs, or     -   (b) a DNA related to the DNA from (a) via the degenerated         genetic code.

The expression “a DNA differing by one or more base pairs” indicates that its partial sequences coding for the individual fragments differ from the corresponding partial sequences of the DNA coding for the fusion protein of FIG. 1 or FIG. 2. The differences may show in terms of additions, deletions, substitutions and/or inversions of individual base pairs. Reference is also made to the above explanations on the individual fragments. A preferred DNA of FIG. 1, which codes for BPVL1 (1-469) and BPVE7₁₋₁₂₇ or BPVE7₁₋₅₄, was deposited as pVL1393-BPV1L1/E7₁₋₁₂₇ or pVL1393-BPV1L1/E7₁₋₅₄ with the DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen [German-type collection of microorganisms and cell cultures]) under DSM 12628 or 12627 on Jan. 14, 1999.

A DNA according to the invention may be present as such or in combination with any other DNA. In particular, a DNA according to the invention may be present in an expression vector. A person skilled in the art is familiar with examples thereof. In the case of an expression vector for E. coli, these are e.g. pGEMEX, pUC derivatives, pGEX-2T, pET3b and pQE-8. For the expression in yeast, e.g. pY100 and Ycpad1 have to be mentioned while e.g. pKCR, pEFBOS, cDM8 and pCEV4 have to be indicated for the expression in mammalian cells. The bacculovirus expression vector pAcSGHisNT-A and pVL 1393 are especially suitable for the expression in insect cells.

The person skilled in the art is familiar with suitable cells to express the DNA according to the invention, which is present in an expression vector. Examples of such cells comprise the E. coli strains HB101, DH1, x1776, JM101, JM 109, BL21, SG 13009, and DH5_(α), the yeast strain Saccharomyces cerevisiae and the mammalian cells L, NIH, 3T3, FM3A, CHO, COS, Vero and HeLa as well as the insect cells sf9.

In addition, the person skilled in the art knows conditions of culturing transformed or transfected cells. He is also familiar with methods of isolating and purifying the fusion protein expressed by the DNA according to the invention. He also knows methods of isolating and purifying the VLPs obtained by folding or collecting the fusion protein.

Another subject matter of the present invention is a kit. Such a kit comprises one or more of the following components:

-   -   (a) a cVLP or cC according to the invention,     -   (b) a fusion protein according to the invention,     -   (c) a DNA according to the invention, and     -   (d) common auxiliary agents, such as carriers, buffers,         solvents, controls, etc.

One or more representatives of the individual components may be present each. Regarding the individual terms, reference is made to the above explanations. They apply here analogously.

By means of the present invention it is possible to immunize ungulates, in particular horses, against sarcoids. The immunization comprises both the induction of antibodies and the stimulation of cytotoxic T cells which are directed against BPV. It is thus possible to take prophylactic and therapeutic steps against sarcoids of ungulates, in particular horses.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the amino acid and DNA sequences of fusion proteins according to the invention which comprise a fragment of the L1 proteins from BPV1, namely 1-469 or 1-472, and BPV1/2 E6 or E7 proteins or fragments thereof. The L1 fragment from BPVI (1-469) has the additional amino acids DID at the C terminus (470472; TATCGATAT). They do not originate from the L1 protein but from the restriction site EcoRV/ClaI inserted in the DNA. The L1 fragment from BPV1 (1-472) has the natural amino acids GAG at the C terminus (470-472; GGGGCAGGA). The E6 fragments from PBV1/2 comprise the amino acid sequences 1-55, 47-101 or 83-137. The E7 fragments from BPV1/2 comprise the amino acid sequences 1-54, 46-100 or 72-127. The fusion proteins may be present in cVLPs or cCs according to the invention (SEQ ID NOs: 1-10)

FIG. 2 shows the amino acid and DNA sequences of fusion proteins according to the invention, which comprise a fragment of the L1 protein from BPV2, namely 1-469 or 1-472, and BPV1/2 E6 or E7 proteins or fragments thereof. The L1 fragment from BPV2 (1-469) has the additional amino acids DID at the C terminus (470-472; TATCGATAT). They do not originate from the L1 protein but from the restriction site EcoRV/ClaI inserted in the DNA. The L1 fragment from BPV2 (1-472) has the natural amino acids GAG at the C terminus (470-472; GGGGCAGGA). The E6 fragments from BPV1/2 comprise the amino acid sequences 1-55, 47-101 or 83-137. The E7 fragments from BPV1/2 comprise the amino acid sequences 1-54, 46-100 or 72-127. The fusion proteins may be present in cVLPs or cCs according to the invention (SEQ ID NOs: 11-20).

The invention is explained by the below examples.

EXAMPLE 1 Production of cVLPs or cCs According to the Invention

(A) Production of the 1-469 Fragment of the L1 Protein from BPV1

An expression plasmid coding for the L1 protein from BPV1, pUC19-BPV1-L1, is used as a basis. It is inserted in a PCR reaction in which the following primers 1 and 2 are used whose 5′ ends on the L1 gene from BPV1 are opposite each other. Both primers carry a short spacer sequence (AAA) and an EcoRV cleavage site (underlined) at the 51 end. Primer 2 additionally contains a stop codon (TGA); The L1-specific sequences are printed in boldface.

                    7015                        6986 Primer 1. AAAGATATCTTGCTGTGCTAAAAATCTTCTTCCCAAGGG (SEQ ID NO:21)                      7038                         7066 Primer 2. AAAGATATCTGAGAAAACGAAGAATTAGCCAAAAAACTTCC (SEQ ID NO:22)

Resulting PCR products are purified, cleaved using EcoRV and circularized with T4 ligase before they are used for transforming E. coli DH5_(α) cells. Clones are obtained which are tested for the presence of an EcORV cleavage site which is not present in either the L1 gene or the vector. Following sequencing, it shows that one of these clones codes for the 1-469 fragment of the L1 protein from BPV1. This clone is referred to as pUC BPV1-L1_(Δ)AC.

(B) Production of Fragments of the E7 Protein from BPV1

An expression plasmid coding for the E7 protein from BPV1, pUC19-BPVI-E7, is used as a basis. It is inserted in a PCR reaction which uses the following primers 3, 4 and 5. Primers 3 to 5 contain a spacer (TTTT) and an EcoRV cleavage site (underlined) at the 5′ end. Primer 3 additionally contains the sequence GAT (underlined, in italics) so as to generate a Clal cleavage site (ATC GAT) overlapping with the EcoRV cleavage site (to identify the insert in sense orientation) and to insert an additional Asp. Primer 5 additionally contains a stop codon. The E7-specific sequences are printed in boldface. Primers 3 and 4 are used to amplify the complete gene of the E7 protein while primers 3 and 5 are used for the amplification of the 1-54 fragment of the E7 protein.

                  474 start                                 508 Primer 3: TTTTGATATCGAT ATGGTTCAAGTCCAAATACCCATAGAAAC (SEQ ID NO:23)                       862                                  833 Primer 4: TTTTGATATCTTATCGTTTGCCATGACGCTCGCGAGATTC (SEQ ID NO:24)                      Stop 640 610 Primer 5: TTTGATATCTTATCGCTTCCTAGTAGGACGGCCGAAATGGCAC (SEQ ID NO:25)

Resulting PCR products are purified, cleaved using EcoRV and inserted in the expression vector bluescript via the EcoRV cleavage site. Having transformed E. coli DH5_(α) cells, clones are obtained which are tested for the presence of two EcORV sites, none of which is present in the E7 gene and only one of which is present in the vector. Following sequencing, it shows that two of these clones code for the complete E7 protein or for the 1-54 fragment of the E7 protein. The first clone is referred to as bluescript BPV1-E7 and the second clone is designated bluescript BPVI-E7₁₋₅₄.

(C) Production of Fusion Proteins According to the Invention

After cleavage with EcoRV, the E7 sequences are isolated from the bluescript BPV1-E7 and bluescript BPV1-E7₁₋₅₄ clones obtained in (B) by means of agarose gel electrophoresis and inserted in the EcoRV cleavage site of pUCBPV1-L1_(Δ)AC of (A). After transforming E. coli DH5_(α), clones are obtained and sequenced. It shows that two of these clones code for a fusion protein which comprises fragment 1-469 of the L1 protein and the E7 protein or the fragment 1-54 of the E7 protein. The first clone is referred to as pUCBPV1L1_(Δ)CBPVE7₁₋₁₂₇ and the second one is designated pUCBPV1L1_(Δ)CBPVE7₁₋₅₄.

(D) Production of cVLPs or cCs According to the Invention

The BPV sequences of pUCBPV1L1_(Δ)CBPVE7 or pUCBPV1L1_(Δ)CBPVE7₁₋₅₄ are cleaved from the vector using Bam HI and inserted in the Bam HI cleavage site of the transfer vector pVL 1393 (Invitrogen company). Clones are obtained after transforming E. coli DH5_(α) cells. Two of these clones have the above BPV sequences, one clone being referred to as pVLBPV1L1_(Δ)CBPVE7 and the other clone being designated pVLBPV1L1_(Δ)CBPVE7₁₋₅₄. The clones are co-transfected together with linearized baculovirus DNA (Baculo-Gold, Pharmingen) in SF9 cells by means of the calcium phosphate precipitation method. cVLPs or cCs according to the invention are obtained which are purified according to the method of Muller et al., Virology 234, 93-111. They contain the fusion proteins BPV1L1_(Δ)CBPVE7₁₋₁₂₇ or BPVL1_(Δ)CBPVE7₁₋₅₄.

EXAMPLE 2 Immunization of Horses Against Sarcoids

Two healthy horses and two horses operated on sarcoids are used. They are given by injection 100 μg-1 mg of the cVLPs or cCs of (D) +/− adjuvant. A booster injection with the same amount of VLPs is made after 14 days. Blood is withdrawn from the horses at different times and tested for induction of antibodies or stimulation of cytotoxic T cells directed against BPV. For this purpose, the methods described in Roden et al., Journal of Virology, (November 1994), 7570-7574 or Brostrom et al., Am. J. Vet. Res. 7, (July 1996), 992-999, are carried out.

It shows that both antibody induction and stimulation of cytotoxic T cells directed against BPV have occurred in the healthy horses. It also shows that the formation of relapses has been prevented in the horses operated on sarcoids as compared to the controls treated with placebos. 

1. Chimeric virus-like particles (cVLPs) or chimeric capsomers (cCs) from BPV, which contain a fusion protein consisting of the amino acid sequences 1-469 or 1-472 of SEQ ID NO: 1 or 11, and the amino acid sequences 1-55, 47-101 or 83-137 of SEQ ID NO: 3 or 17 or the amino acid sequences 1-54, 46-100 or 72-127 of SEQ ID NO: 5 or
 9. 2. A fusion protein of BPVL1 and the E6 or E7 protein from BPV1 or BPV2 consisting of: the amino acid sequences 1469 or 1-472 of SEQ ID NOS: 1 or 11, and an amino acid chosen from the group consisting of the amino acid sequences 1-55, 47-101 or 83-137 of SEQ ID NOS: 3 or 17 or the amino acid sequences 1-54, 46-100 or 72-127 of SEQ ID NOS: 5 or
 9. 3. A DNA coding for the fusion protein according to claim 2, wherein the DNA comprises a combination of SEQ ID NOS: 2 or 12 and SEQ ID NOS: 4, 6, 8 or 12, or a degenerate sequence thereof.
 4. An expression vector containing the DNA according to claim
 3. 5. A method of immunizing ungulates against sarcoids comprising the step of injecting cVLPS or cCs from BPV to the ungulates, wherein the VLPs or cCs contain a fusion protein which comprises a fragment of the L1 or L2 protein from BPV and an early protein from BPV.
 6. The method of claim 5, wherein the fragment of the L1 protein comprises the amino acid sequences 1-469 or 1-472.
 7. The method of claim 5 or 6, wherein the early protein is an E6 or E7 protein.
 8. The method of claim 7, wherein the fragment of the E6 protein comprises the amino acid sequences 1-55, 47-101 and/or 83-137.
 9. The method of claim 7, wherein the fragment of the E7 protein comprises the amino acid sequences 1-54, 46-100 and/or 72-127.
 10. The method of claim 5 or 6, wherein the BPV is the BPV1 type or BPV2 type.
 11. The method of claim 5 or 6, wherein the immunization results in a prophylaxis effect and/or treatment of sarcoids.
 12. The method of claim 5 or 6, wherein the ungulates are horses.
 13. The method of claim 5 or 6, wherein the fusion protein comprises the amino acid sequences 1-469 or 1-472 of SEQ ID NO: 1 or 11 and the amino acid sequences 1-55, 47-101 or 83-137 of SEQ ID NO: 3 or 17 or the amino acid sequences 1-54, 46-100 or 72-127 of SEQ ID NO: 5 or
 9. 